


They're Two Sides of the Same Coin

by vinegarce



Series: Heroes AU [1]
Category: Haikyuu!!
Genre: But not that much, Day 3, Heroes, It was supposed to be sakuatsu, M/M, Villains, and not in a fun way, but i hate formatting, but like its not very fluffy, but now its just brothers and sadness, hero/villain au, i mean they live so i guess its fine, i wrecked his soul, im sorry, its from kiyoomi's pov, maybe ill write atsumus but thats even more the sad, poor atsumu, sakuatsufluffweek2021, this was supposed to be short enough for twitter
Language: English
Status: Completed
Published: 2021-02-17
Updated: 2021-02-17
Packaged: 2021-03-12 11:01:13
Rating: Teen And Up Audiences
Warnings: Graphic Depictions Of Violence
Chapters: 1
Words: 2,863
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/29508693
Author URL: https://archiveofourown.org/users/vinegarce/pseuds/vinegarce
Summary: Miya Osamu had been kidnapped by one of the most notorious crime syndicates in Tokyo.The news was a shock because the twins were top heroes. The kidnapping of a hero meant that they needed to act. And fast.Not that Atsumu would allow them to do nothing. He stormed into HQ simultaneously in tears and demanding to be on the mission team.Somehow, Kiyoomi had been paired up with Atsumu on the mission to save Osamu.
Relationships: Miya Atsumu/Sakusa Kiyoomi
Series: Heroes AU [1]
Series URL: https://archiveofourown.org/series/2167656
Kudos: 9





	They're Two Sides of the Same Coin

Kiyoomi expects to find Miya Atsumu crying in one of Heroes HQ’s far corners after a debrief on their latest mission. He had, however, not expected it when they all thought his twin Miya Osamu had been kidnapped by one of the most notorious crime syndicates in Tokyo. 

The news was a shock because the pair were top heroes. Until now, these criminals had evaded capture but hadn’t had it out for the heroes. Tending to avoid confrontation. The shift in the mode of their operation and kidnapping of a hero meant they needed to act. And fast.

Not that Atsumu would allow them to do nothing. He stormed into HQ simultaneously in tears and demanding to be on the mission team.

Somehow, Kiyoomi had been paired up with Atsumu on the mission to save Osamu. Atsumu’s usual partner was Osamu. Kiyoomi usually worked alone. This meant that they had a few issues initially. Atsumu was in a constant state of distress because of his brother. He and Kiyoomi had eventually worked it out because it was only for one mission. Atsumu would have his twin back, and things would go back to normal.

They had to work fast, which meant that they cared more about where and how than the why of the crime syndicate’s actions. There was something against heroes brewing. But Osamu’s rescue was first and foremost. 

They also knew that they couldn’t just walk in, get Osamu and walk out. If it were that easy, Osamu would have gotten away. At least according to Atsumu. Kiyoomi guessed he had a point. All the top heroes were at the top for a reason.

Kiyoomi knew the rescue was also going to give them information from whatever Osamu gathered. He was a smart hero. He wouldn’t give anything away and could get people to talk without them realizing it.

They had arrived at the warehouse where Osamu was supposedly being held with two other heroes. It had taken over a week to discover the hiding place. They needed the backup since, despite the intell gathered, they had no idea how deep the group’s membership ran. 

Kiyoomi and Atsumu slipped through a broken window on the third level. There were hardly more than large pipes there since the story was for height. 

“Are we sure that this was the right place?” Kiyoomi asks in a low whisper. “There’s hardly anyone here. You would think they would need more people to keep Osamu…”

The rest of his thought goes unfinished, not wanting to give Astumu the idea his twin might be dead. He can’t have him acting rashly and ruining the mission. They can’t afford more deaths.

“There’s supposed to be a meeting tonight. That’s why frosted tips and the redhead needed back up this early to infiltrate the floor.” Atsumu replies after he’d settled on the pipes.

“I know that.” Hisses Kiyoomi. “Also, why’d they have those two on the floor? They’re rowdy and have recognizable hair.” He also doesn’t mention that Atsumu and Osamu have pretty weird hair.

Atsumu shrugs, and they go back to sitting in silence.

After about half an hour, hooded figures start to trickle in. Kiyoomi thanks his stars that when the room seems pretty full, he doesn’t notice the two heroes’ presence. 

He spends too long looking for them just to be sure they don’t stick out and doesn’t notice the figure who arrives and steps up onto the concrete platform in front of one of the doors. The man raps his fingers on the railing separating him from the rest of the hooded people.

He begins to talk, but Kiyoomi can’t hear what’s being said. He guesses that having someone on the floor makes sense now. He turns to tell Atsumu they should move down since they need to be closer to know when to get Osamu. 

He curses Atsumu internally when he sees him already on the way to the second floor and rushes to follow him. At least as fast as one can go when trying to navigate an echoing warehouse.

When he finally gets back to Atsumu, Kiyoomi is about to berate him for rushing ahead and how he shouldn’t do anything before they are sure of Osamu’s location. Still, he can hear the lone figure more clearly, so he settles for a silent conversation.

The face he directs at Atsumu clearly says, “What the hell? I know I’m not Osamu, but we still need to communicate to make this work.”

Atsumu rolls his eyes and levels Kiyoomi with an “I tried to get your attention. You ignored me. So I moved closer since you wouldn’t get to yell at me here.”

Kiyoomi glares at him for a moment, but Atsumu’s head suddenly whips around to the figure speaking. 

His eyes go wide. He makes a move to get closer again.

Kiyoomi is not having this and grabs Atsumu’s arm holding him in place. 

He mouth’s “What is it?” but Atsumu’s attention is already back on the man. So Kiyoomi shakes him and repeated his silent question.

Atsumu just looks back at the figure again and then back to Kiyoomi. 

He finally just squints his eyes and mouths, “He seems familiar.” His brows furrow some more. “Unsettling.” He whispers, turning back to the scene before them.

Kiyoomi finally spends a moment inspecting the man speaking to the crowd. He still can’t hear what he’s saying. The timbre of his voice does seem familiar. But he can’t place it.

They’ve moved slightly closer again when Atsumu freezes and throws out his arm. It takes most of Kiyoomi’s willpower not to throw Atsumu when he’s nearly clotheslined. 

He’s about to drag Atsumu down to where there better cover when he finally understands why they stopped. 

The voice of the man on the concrete platform can be heard clearly.

“And now I know I’ve talked for an hour, but I’ve received a signal that our leader has finally arrived, along with apprehended heroes!”

A mix of jeers and cheers rise from the crowd as the figure turns to welcome the crime leader. As the man turns, Kiyoomi gets a glimpse of the man.

His head whips around to Atsumu, who’s staring at him, mouth wide.

“Holy shit, it’s Suna. The goddamn bastard. Thought we had him locked up?” Atsumu whispers, a bit of panic coloring his tone.

“He’s not what we’re worried about right…” Kiyoomi’s voice cuts off when he sees that the heroes being dragged out in front of a new man, presumably the leader, by about four guards.

“Shit, they got Bokuto and Hinata.” Now the panic is in Kiyoomi’s voice.

“No, Kiyoomi! We need to wait until we figure out where they have Osamu before making a move. Plus, the leader just arrived, so going now may get us all killed.”

The crowd’s noise finally dies down at the wave of a hand from the man in charge. Another series of gestures, the four guards push Bokuto and Hinata down and tie their ankles so they can’t move. When finished, they move away towards the doors, likely on the lookout for more heroes.

Suna Rintarou, previously thought to be in jail for petty theft and now the right-hand man to the leader of Tokyo’s biggest crime syndicate, gestures for everyone’s attention. 

The leader nods at him and begins talking about the syndicate’s plans to start their extermination of the heroes finally. About how these people are given destructive privileges that they abuse more than the police forces. How they will put all of their past work to use. Soon enough, the crowd has worked itself into a frenzy. Demands for the blood of the heroes must be spilled in order to restore society.

Kiyoomi can’t believe what he’s hearing, and it seems Atsumu is also flabbergasted since they’re rooted to the spot.

“Well, since you all are so eager, let us begin then.” The leader’s calm voice cuts over the crowd. They fall silent.

The silence is deafening as the man walks over to where the two heroes kneel.   
“Tonight, we draw first blood for the New Age.”

He pulls one long curved blade from his belt, which is duplicated in the other hand in gleaming ice.

Before Kiyoomi can react, Atsumu makes a loud noise followed by one word in a strangled voice.

“Osamu.”

In the same moment, Kiyoomi tackles Atsumu out of the way as one of those wicked knives flies towards them. All hell breaks loose below as everyone’s attention turns to the two of them.

In the brief moment they're on the ground, Kiyoomi yells, “You have to either get out of here or help me get them! We need to deal with this later.”

He then drags them to their feet, shouts “Move, idiot!” 

He launches over the walkway and activates his powers as he sails down—nine duplicates land around him. In sync, they attack, clearing a path for Kiyoomi. 

He ducks under the first of one hooded man and uses his momentum to kick the legs out from under the next.

He feels three duplicates go down by the time he reaches Bokuto and Hinata.

The three Kiyoomi’s disappear and reappear to help him.

As soon as they’re untied, they spring into battle. Quite literally, as Hinata launches off the concrete and lands amidst a group of guards at the door. His impact blows them all face-first into the pipes between the second and third levels. Bokuto sprouts wings, and with a mighty flap sending an onslaught of bullets and other weapons in the other direction.

The Kiyoomi’s clear any remaining criminals out of their path as the heroes escape. Their first plan to escape and regroup with their new intel at HQ.

As soon as they pass the threshold, Bokuto’s claws grab him, and he pulls his copies back into himself. 

Panting, he looks for Atsumu. Hopefully, he had been able to escape.

His hopes are dashed as one of the warehouse walls explodes in a giant ball of fire.

Bokuto drops him in surprise.

“Hoo, shit! Sorry!!”

He hits the ground.

Kiyoomi sprints back into the warehouse. 

As everyone is running from the chaos above, the few people left scatter as he dispels his duplicates once again.

A large chunk of the concrete takes one out as they all rush upwards. Before the duplicate is crushed, Kiyoomi reforms him at his side.

Kiyoomi is almost surprised when he sees Atsumu fighting Suna. He sends blasts of fire towards his opponent. Sun stands lazily, flicking his fingers and sending dark ribbons of energy to dissipate the attacks. He truly seems unbothered by Atsumu, lifting only his fingers.

Suna hasn’t noticed Kiyoomi’s approach, most of his attention on Atsumu’s flurry of fire, so he reforms three Kiyoomi’s around Suna.

Two on the sides. Hands grabbed. The third forms just after a fire blast. A blow to the head. Suna is out.

Kiyoomi turns to Atsumu. “I thought I told you to get out of here! We need to deal with this later.”

“So you’re who they put him with.” 

The voice shoots ice into his veins. Kiyoomi can’t act now. So he’ll let Osamu talk. Hopefully he... No, he has to... get Atsumu out of here. He shouldn’t face his brother so soon when his emotions are likely fraying and making him unfit for a fight.

“I’m surprised. You always seemed cold, Sakusa. You would have made for a better second seeing as you took mine out so quickly. But,” He turns to his twin, “I guess my specialty was knowing your weaknesses.”

“You… You set me up.” Kiyoomi had never heard Atsumu’s voice so soft. It spoke volumes to the betrayal he likely felt. “You’re my brother. You were always the good one. How did this… What happened?” 

“What happened was that you are weak. Too naive to see what I saw. You’ve always stood behind a shield. First, me. Now him.” 

Kiyoomi could feel the chill in the air, how those words flayed Atsumu.

Atsumu let out a small noise. And it was enough to pull him into action. 

All ten of him surrounded Osamu. They all attacked. A knife thrown. Punches. Kicks. Attacks from above a sweep from below.

A knife froze here. A punch narrowly avoided there. Osamu narrowly avoided Kiyoomis’ swarm. He sends his frozen daggers into them.

Kiyoomi does his best to avoid the daggers. He reforms himself when he’s hit.

The true Kiyoomi stays in the group that attacks from slightly further away. The worst thing to do is to get himself too close.

Osamu is taking out Kiyoomis faster. He manages to grab two with his hands—an ice blast knocking the rest back long enough for him to freeze them. 

Kiyoomi breaks them down, but he cannot reform himself. The cells have been slowed down too much by the cold.

Slowly but surely, Kiyoomi finds himself unable to revive his copies. It’s too cold. He can’t reabsorb them. It’ll slow him down. But he becomes vulnerable without the extra protection.

It’s just him now. He’s been beaten down to his hands and knees. His breathing is ragged. He can see its mist as he exhales. He feels himself around him, but he’s not there in the way it counts. God, if Atsumu is still here…

“See, Tsumu.” Fuck, they’re doomed. “You’re still letting others handle your battles. Not that it did much. He doesn’t last in long battles.”

Kiyoomi is going to go in one last time. Even if it’s the end of him, he needs Atsumu to survive this. He…

An icy pain shoots through his rib cage. His train of thought is cut off. He hasn’t been able to protect his partner. His body gives out.

He’s not quite sure what happens next. Before his eyes slip closed, he sees Atsumu consumed in flames.

The heat is nice, he thinks, as it grows in intensity. The last thing he’s able to do for a while is to use the heat to retrieve the matter of his copies.

He comes to a while later. Maybe it’s been minutes; maybe it’s been hours. It’s so hot now. His brain supplies that if he isn’t dead now, the temperature fluctuation will get him too sick to heal for sure.

He hears people speaking distantly.

“Don’t jostle them too much bo!”

He misses what’s next because he notices that he’s bobbing.

“I know, but Kageyama’s almost here. Hopefully, he’s got something to stabilize them.”

Kiyoomi feels his pain wash over him anew and passes out again.

\---

He’s been out for three days, is what Hero Doctor Ushijima says. The heat that Astsumu gave off when he fought his brother allowed him to save all his copies (they won’t let him check for two weeks, much to his chagrin). Saving his copies also gave him a much higher healing rate than even most heroes. Whatever Kageyama came up with was kept him and Atsumu stable enough to get back to HQ.

Ushijima almost had to sedate him when he first woke up because he didn’t know that Atsumu had survived. He was going to split himself just to escape the staff to find Atsumu. He’s next door. They’ll let him visit when he’s awake and settled.

Of course, as soon as that happens, they’re called into the briefing.

Atsumu didn’t kill his brother, but they were in equally terrible condition at the end. 

Suna was apprehended, but Osamu couldn’t be found on the scene.

Bokuto will forgive having his wings singed to save them because he dropped Kiyoomi.

HQ will be sending more long-range heroes when they attempt to apprehend Osamu again.

Kiyoomi expects to find Miya Atsumu crying in one of Heroes HQ’s far corners when they are finally released from the brief. He made a scene when this whole ordeal began. 

But instead, Kiyoomi just finds him eating with others in the cafeteria. Bokuto and Hinata gesticulating wildly for Kageyama and Hoshiumi.

Or standing in the bathroom washing his hands longer than Kiyoomi does, while some of the newer heroes brag about their first missions to each other. 

He finds him when they’ve been told they are well enough to go home and not stay in HQ’s hospital for monitoring and post-trauma training. He’s sitting in the hallway just staring blankly at the wall.

Kiyoomi doesn’t know how broken Atsumu is after that night, but he understands the desperation of fighting for yourself and someone else when life hangs in the balance.

He doesn’t say anything just sits down as well.

After some time, Atsumu lays his head on Kiyoomi’s shoulder.

“He’s my brother.” The tears finally start after so many weeks. Kiyoomi pulls Atsumu into a hug, and the other man clings to him in return.

When his tears finally die down, Atsumu goes to pull away.

“Let’s just stay like this for a little longer,” Kiyoomi mumbles into Atsumu’s hair pulling him close once again.

He feels Atsumu nod.

They find comfort in each other. It helps ease the pain of getting back to work.

**Author's Note:**

> Notes: powers: Kiyoomi: multiples - within him, he houses enough cells for 10 of him. This is part of why he hates crowds. He houses his own crowd.  
> The twins: Osamu - ice, Atsumu - Fire, idk its two sides of the same coin, but I feel like ice has a lag up on fire because heat intake (Osamu removes heat to create cold things)l is easier than heat output (Atsumu has to heat things up which uses energy)  
> Hinata - power jumps, sort of like in HQ where he can meet Kaegyama’s sets with his speed and jumps here. He uses that power for immense impact and can blow everyone away.  
> Kageyama is like their tech person, sort of like Q in 007. He’s the genius techie.  
> Suna - dark whip; he’s a bad guy, sorry :( he can expel dark ribbons of energy from his fingertips, He doesn’t like close combat because then he has to move more, but with this, he can keep people at bay. But if you can get close enough, he bails because that’s not worth it.  
> Ushijima - he’s a healer, but also like a tank, good for a gunfight  
> Plus, I have more because this may turn into a multi-story thing eventually? Like multiple in-universe drabbles.
> 
> Also, as I was writing this, I didn’t even notice half of the little nuances, but like Atsumu easily recognizes suna’s voice, a villain he's interacted with a few times. Still, it takes the use of Osamu’s powers for him to notice? Like, wow, that’s cold (bad dum tis, I know I hate myself for that as well). Also, the reason Bokuto and Hinata are so subdued during Osamu’s speech is because he's keeping them cold because lethargy makes it hard for them to use their powers. Also, Osamu is sorta like the perfect capturer, which is probably why he and Atsumu are top heroes (well… until he becomes evil)
> 
> And the big confrontation where we see that even under emotional duress, Atsumu protects his partner first, even if he’s thrown into a situation where his brother, his life partner, becomes his enemy within minutes of this happening. And like kiyoomi hates working with others because like he usually thinks he’s fine alone, so like when he thinks “I didn't save my partner,” I'm *sob* 
> 
> They’re definitely too busy and stuff to like totally realize they are in love yet. But we will get there. ( i think I may have to squeeze some side ships outta this because clearly, this is going to be a mostly angst au)
> 
> Also, I'm sorry that this became so angsty. I meant for it to be like a small thing to get to atsumu needing a hug from kiyoomi, and here we are, crying in the club sdkjsdkslhgdk


End file.
